Would high intensity pulses of electrons, brute forcing through the magnetic field, be an effective method of injecting electrons into a polywell? Instead of finessing their way in along a field line, push the magnetic field out of the way for a moment.

The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)